Centralized traffic controlling system



J. wlcKs March 18, 1-941.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed m 29, 1936 15 Sheets-Sheet l o om on INVENTOR. JOHN WIICKS, 2%Z

ATTORNEY.

J. WICKS March 18, 1941 CENTRALIZED TRAFFIC CONTROLLING SYSTEM 15 Sheets-Sheet 3 Filed May 29, 1936 h wm .mwm v m gm m HWW M m o .00% w m w 4 .I o A 8% J J. WICKS March 18, 1941.

CENTRALI ZED TRAFFIC CONTROLLING SYSTEM 15 Sheets-Sheet 4 Filed May 29, 1936 J. WICKS March 18, 1941.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed llay 29, 1956 15 Sheets-Sheet 5 m Jmm .223 0250 0 mmmIUF Qw5 INVENTOR. JOHN WICKS- M ATTORNEY.

J. WICKS March 18, 1941.

CENTRALIZED TRAFFIC CONTROLLING SYSTEI Filed lay 29, 1935 is Sheets-Sheet s hwm INVENTOR.

JOH N WICK S ATTORNEY.

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CENTRALIZED TRAFFIC CONTROLLING SYSTEI Filed llay 29, 1936 15 Sheets-Sheet 8 1:23 @2500 ZOWF Pm QJmE ATTORNEY.

March 18, 1941. J. WlCKS 2,235,346

CENTRALIZ ED TRAFFIC CONTROLLING SYSTEM Filed May 29, 1956 15 Sheets-Sheet l0 TRAIN SIGNAL START START 4 Ria l 095 T T s T 1 I H092 M091 SLOW START AND DISTRIBUTING RELAYS FIG. 10

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INVENTOR.

JOHN WICKS ATTORNEY.

March 18, 1941. J. w11 s 2,235,34

CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed May 29, 1936 15 Sheets-Sheet 11 FIG. 11

I: Ta I 1 a TRACK INTERLOCK .E'

RELAYS I i 1 11s I 105 NH? E. Q: g K POSITION CONTROL RELAYS TRACK SIGNAL RELAYS INVENTOR. JOHN WICKS ATTORNEY.

March 1;, 1941. J. w|Ks I 2,235,346

CENTRALIZED TRAFFIC CONTROLLING SYS'IEII RELAYS Filed lay 29, 1936 15 Sheets-Sheet l3 )7 I FIG. 13

l G TRACK l INTERLOCK TRACK SIGNAL RELAYS POSITION CONTROL RELAYS i I A374 g? i 1461 l SLOW, 4 m .o v I i I I I 191 I 'e-mo I 1192 I 1193 I C 1365 136s I 1366 1366 i i IN VENTOR.

ATTORNEY.

March 18, 1941. J. wicKs 2,235,346

CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed lay 29, 1936 15 Sheets-Sheet l4 TRACK INTERLOCK RELAYS 61'- 145s 1&8 1

c m"- 1 3 1362 1402 I 6H I x I p- 1 i 1464 11 5 SLOWI 14m I 1 I M68 166 R GNAL I POSITION CONTROL RELAYS T ACK RELAYS INVENTOR. JOHN WICKS ATTORNE March 18, 1-941. w c s 2,235,346

CENTRALIZED TRAFFIC CONTROLLING SYSTEI 'Filed May 29. 1936 15 Sheets-Sheet 15 DISPATCHERS ,PANEL 5 8 2} Y 85L KEY-8 KEY-9 KEY-9S FIG. 16

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IN VENTOR.

JOHN WICKS ATTORNEY.

Patented Mar. 18, 1941 PATENT f critics 7 2,235,346 CENTRALIZED TRAFFIG CONTROLLING SYSTEM John Wicks, Oak Park, 111., assignor to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application May 29, 1936, Serial No. 82,568

4 Claims.

This invention relates to centralized trafiic controlling systems for railroads, and more particularly to a system for remotely controlling track switches and signals at a plurality of field stations from a centralized dispatchers station having a track layout panel with symbols which are set in accordance with the actual track and signal conditions in the field.

In the provision of centralized traffic controlling apparatus, not onlyis it necessary to remotely control distant track switches and signals, but it is essential to indicate in the dispatchers office train progress along the railway track, and, further, it is also essential to indicate to the dispatcher the actual positions or conditions of the track switches and signals when such switches and signals are operated under his control.

In accordance with the present invention, the centralized trafic controlling system comprises a plurality of field stations along the railroad track and a centralized dispatchers station. Coding apparatus is provided at the dispatchers station and at each field station for transmitting and receiving codes over a two-conductor line connecting the dispatcherfs station to all the field stations.

Each code transmitted from the dispatchers station to thefield stations, first, selects the. desired field station and then causes the desired operation of the track signal or track switch in the selected field station. The coding apparatus in the field stations transmit codes to the dispatchers stationin response to and in accordance with the operations of the track signals and switches and in accordance with train travel over the track sections. The codes transmitted to the dispatchers station from the field stations cause corresponding indications to be displayed on the dispatchers panel. 1

Each field station corresponds to a plurality of track sections and their associated track switches and signals. The dispatchers station is provided with a panel having a miniature track layout thereon corresponding to the railway track associated with the field station. This panel is divided into units or sections corresponding to the field stations and has train progress lamps, and symbols or lamps corresponding to the track switches and signals of each field station. The panel is also provided with a key for each distant track switch or signal to enable the dispatcher to control the associated panel control relays in accordance with the position such key is actuated to. The panel control relays control the operation of the dispatchers coding apparatus to transmit a code corresponding to the actuated key. These panel control relays are also operated in accordance with the codes received from the field stations to operate the panel symbols or lamps.

The dispatchers coding unit is common to all of the unit panels and transmits outgoing codes, comprising three digits, in accordance with the particular panel unit connected with and in accordance with the particular key and panel control relay which is operated. The dispatchers coding unit also receives incoming codes from the various field stations and operates a step-by-step switch in accordance therewith to operate the proper train-progress lamps and the proper track or signal symbols on the panel.

Each field station is provided With the usual and well-known track interlock relays for controlling the track signals in accordance with the train traific oven .the corresponding track sections. These interlock relays and circuits are not part of this invention, and are shown and described briefly to enable the invention to be fully understood. Associated with the interlock relays at each field station are position control relays which operate the track switches and signals through the interlock relays in response to the certain codes received from the dispatchers station. These position control relays are provided for each track signal or signal, and control the field station coding apparatus to transmit codes to the dispatchers station in accordance with and in response to the operation of such track switches and signals.

A pair of track-signal relays are associated with each track section and are operated in accordance with track occupancy to control the field station coding apparatus to transmit codes in accordance with such occupancy.

Each field station coding unit, transmits outgoing codes comprising three digits, the first two in accordance with the field station which is transmitting and the third in accordance with the particular position-control or track-signal relay which is operated. The field station coding unit also receives incoming codes to operate the proper position control relays in accordance with the codes transmitted from the dispatchers station. All the field station coding units respond to incoming codes fromthe dispatchers station but only one group of position-control relays at a particular field station is selected foroperation due to cross-connections of the code marking relays which are operated by the first two digits.

The first impulse of the first digit in the codes transmitted from the dispatchers station is a prolonged impulse to give the dispatcher preferonce over transmission from the field stations and to condition the field station coding units to receive the transmitted codes. The field station coding units respond to incoming codes only in case the first impulse is a prolonged pulse and, therefore, since the field stations do not transmit this prolonged pulse other field stations do not respond when a field station is transmitting to the dispatchers station. Each field station is prevented from transmitting a code to the dispatchers station when another field station is transmitting or the dispatchers station is transmitting.

The main object of the invention is the provision of new and novel circuit arrangements in a centralized traffic controlling system of the above described type which are efficient and reliable in operation.

Another object of the invention is the provision of an improved coding arrangement which is quicker in operation than those now in use by reducing the code-transmission time for a large system of this type.

Other objects and features of the invention relate to the new and novel circuit arrangements which will be apparent from the following detailed description of the drawings.

Referring now to the drawings comprising Figs. 1 to 18, inclusive:

Figs. 1 and 2 show the dispatchers panelcontrol relays, keys, and signals corresponding to the field station signals shown in Figs. 11, 12, 13 and 14.

Fig. 3, in the upper portion, shows the dispatchers track indicating relays and in the lower portion shows. the start and distributor relays for the dispatchers coding apparatus.

Fig. 4, in its upper portion, diagrammatically illustrates a vertical and rotary step-by-step switch and associated controlling relays and magnets; while in the lower portion meet the sets of dispatchers code-marking relays are shown.

Figs. 5 and 6 show the common dispatchers coding-unit relays.

Figs. 7 and 8 show one of the field station coding units.

Fig. 9 shows the code-marking relays for this particular field station.

Fig. 10 shows the start and distributor relays at this field station.

Figs. 11, 12, 13, and 14 show the track layout and the well known train interlock relays, the

position control relays, and the track-signal relays associated with this field station.

Fig. 15 illustrates a portion of the dispatchers penel corresponding to the field station shown in Figs. 11, 12, 13, and I l.

Fig. 16 shows a detail of the combined key and signal BSL.

Fig. 17 shows a cross section of the mechanical construction of the combined key and signal SSL.

Fig. 1S'shows the manner in which the different figures of the drawings should be placed in alignment.

Throughout the drawings similar reference characters indicate similar apparatus orequipment. Also throughout the drawings the negative and positive battery symbols have beerrused to simplify "the drawings, and it will be understood that where thes symbols are used in the dispatchers station all such symbols are connected to a common battery. The negative and positive battery symbols are also used in the circuits disclosed in the field station to simplify the drawings. It will be understood that a separate battery is used for the track-interlock relays in accordance with the usual practice and another battery is connected to the position-control relays, the track-signal relays, the codingunit relays, the code-marking relays, and the start and distributor relays.

Referring now to that portion of the dispatchers panel illustrated in Fig. 15, it will be seen that the illustrated track sections are each of a different color; that is, the section corresponding to track section 9 of Fig. 11 is blue, the section corresponding to section 8 is red, and the sections corresponding to sections 6 and I are yellow. Each such illustrated section has a round track symbol, such as STPL, STPL, ITPL, and BTPL. These symbols are round glass transparent caps suitably-mounted on the panel and are known as the track-pilot symbols for indicating to the dispatcher the location of trains. Similar round transparent symbols QMSL, 9SSL, ISL, and ESL are also suitably mounted on the panel. These symbols correspond, respectively, to the track signals 9MS, -9SS, IS, and SS in the corresponding field station and are positioned on the panel in accordance with the location of the distant track signals. A lever,'or key-9, is associated with the symbols SMSL and SSSL on the panel and is'operable by the'dispatcher-to controlthe operation of the distant track signals HMS and SSS. A similar lever, or keyI, is associated with the symbol ISL for controlling the distant track signal IS. Ina like manner the key-6 is associated with-symbol GSL for controlling its corresponding distant track signal BSL. The stick key-9S is a turn key which isoperated by the dispatcher when the dispatcher wants only one train to pass over section 9.

The key-'8 isa combined key and signal for both controlling the operation of the corresponding track'switch TS in'the field station (Fig. 12) and for indicating to the dispatcher the operated position of the same. The mechanical construction of this combined "key and symbol is more fully disclosedtin Figs. 16ian'd 17. The upper portion of this key-symbol, as seen in Fig.1'7, comprises a raised rectangular transparent glass portion indicated asBSL. This. raised portion is providedto'enable' the dispatcher to turn the same and is made transparent so that different coloredlights may be visible through it. Asingle lamp is mounted directly behind each sym- I bol ST-PL, 8TPL, "ITPL, and G-TPL, in any suitable manner. These lamps-aresho'wn in Fig. 3 and have corresponding reference characters.

A red and a green lamp are suitably mounted behind the symbol BMSL on-the-panel for visibly indicating to the dispatcher a'red or a green indication. These lamps are shown in Fig. l and are correspondingly labeled-SMSL. In a similar manner 'the red and yellowlamps marked 9SSL, Fig. l, are mounted behind the symbol SSSL on the panel, the red and yellow-lamps marked ISL, Fig. 2, are mounted behind the symbol ISL on the panel, and the red'and green lamps marked ESL, Fig. 2, are mounted behind the symbolBSL on the panel. The red and green lamps marked -8SL, Fig. l, are mounted behind the symbol BSL on the panel as shown in Fig. 17. Each key on the panel controls a-pair of springs as indicated at keys 9, 9S, -I,--and-6 in Figs-I and 2.

--'I'he conductors of cable 5u extend from the fifth level of the vertical and rotary step-by-step switch in the dispatchers station to the panelcontrol relays for controlling the operation and the release of the relays prefixed with the letter C. The conductors of cable 13 extend from'the panel-control relays to contacts of one of the code-marking relays which operatively connect these conductors to the conductors of cable 83 extending to contacts of the digit-counting relays in'the dispatchers coding unit.

The cable 60 includes the conductorsfor opcrating and releasing the track indicating relays shown in Fig. 3 and these conductors terminate in the sixth level of the vertical and rotary stepby-step switch. The panel-control relays shown in Figs. 1 and 2 control an individual start'relay shown in Fig. 3. A second start relay 343 is also shown in Fig. 3 which will be operated from the control relays of a second panel unit.

While only two start relays and one panel .unit are shown, it will be understood that additional panel units and start relays may be added. The distributor relays shown in Fig. 3 automatically select the proper group of code-marking relays in accordance with the particular start relay operated.

Certain of the code-marking relays are crossconnected by conductors such as 413 and 479, in accordance with the particular numerical designations'of the corresponding group of panelcontrol relays.

be provided for each panel unit. The vertical and rotary step-by-step switch disclosed in the upper portion of Fig. 4 has one-hundred bank contacts accessible to wiper 432. The onehundred bank contacts of this switch are divided into ten levels of ten bank contacts each. This type of switch is of the well-known type of Strowger switch used in automatic telephone systems. The switch-controlling relays and magnets, and the code-marking relays are connected to the dispatchers coding unit shown in Figs. 5 and 6.

A pulse generating relay 352 is shown in Fig. 5 having a weighted vibratory armature for controlling the generation of impulses which are counted on the digit-counting relays and the space-counting relays shown in Fig. 6. The conductors 531 and 563 extend from the dispatchers station through all of the field stations in series. The dispatchers coding unit has a line relay 503 which responds to both incoming and outgoing pulses over line conductors 501 and 533. Each field station is provided with a similar line relay which also responds to both incoming and outgoing pulses over these two line conductors. Each field station coding unit is similar to the dispatchers coding unit and has a pulse generating relay and counting relays. The field station code-marking relays shown in Fig. 9 operatively connect the field station coding unit to its associated position-control or track-signal relays over the conductors shown in the operate cable OC, the release cable RC, and the track indicating cable TIC.

Each field station unit has a signal-start relay controlled from the position-control relays and a train-start relay controlled from the track signal relays. The associated distributor relays in Fig. 10 cause the operation of the proper codemarking relays so that the track-signal relays or the position-control relays are connected to the field station coding unit. In case this particular field station has a number of traflic governing A separate group of code-mark- K ing relays s milar to that disclosed in Fig. 4 will devices in excess of five to control, then a separate start relay and .a separate code-marking relay group are provided for each five trafilc governing devices. Such a field station is then divided into units of five traffic governing devices each, and each such unit has separate start and code-marking relays. As an illustration, in the lower right-hand corner of Fig. 10 is shown a rectangle, labeled field station unit 2, which is similar to the field station units shown in Figs. 11, 12, 13, and 14. I

Figs. 11, 12, 13, and 14 show a plurality of track sections numbered 9, 8, I, and 6. The take-siding signal SSS and the main track signal HMS are for routing trains from leftto right over the track switch TS to section or over the track switch TS. to section 6. Signal IS is for controlling train travel over the track switch TS from the siding, while signal BS is for controlling train travel from right to left over the main line section and the track-switch TS. The track switch TS is operated in the well-known manner by the motor SM which in turn is controlled by the polar relay BWR. The switch contacts I213 and I2|"| are contacts which are operated by the track switch TS and which are only operated to circuit-closing positions when the track switch is in either one of its operated positions. The trackinterlock relays and associated circuits are not part of this invention and are disclosed to enable the invention to'be more fully understood. The position-control relays and the track-signal relays are grouped in accordance with their corresponding signals and sections of tracks. These latter relays are connected by conductors included in the operate cable DC, the release cable *RC, and the track-indicating cable TIC, to the code-marking relays.

Fig. 15 shows one panel unit of the dispatchers panel which corresponds to the field station shown in Figs. 11, 12, 13, and 14, and the different symbols of this panel are controlled in the manner shown in the circuit drawings in Figs. 1, '2, and 3. The combined key and signal 8SL is mounted on "the panel 25 by means of machine screws 29 extending through a flanged sleeve 32, Fig. 17. Semi-circular clamps 35 are clamped around the sleeve 32 and have extensions (not shown) extending down to the brackets 31 upon which the springs I", the springs 26, 21, and 28, and the spring 23 of the detent 23 is mounted. The red and green lamps are mounted in the lamp springs 26, 21, and 23 in the well known manner. mounted within the sleeve 32. The sleeve 33 is secured to the flanged sleeve 34 by means of a set screw (not shown), while the fiber disc 23 is secured to the flange of sleeve 34. Inside of rotatable sleeve 33 is inserted the sleeve 3| holding the glass portion 33 by the .crimped edges of sleeve 3 I, as'shown. A slot 3| keys the sleeve 3| to the sleeve 33. 33 is a circular glass piece having a raised rectangular portion 88L. Thev raised rectangular glass portion 8SL is transparent. The lower part of the glass piece 33 is glazed black as shown in Fig. 15. The raised portion 8SL is rotated by the dispatcher, in the direction indicated by the arrow, to cause the sleeves 3| and 33 to rotate the sleeve 34 and fiber disc so as to close springs IT! by the cam portion 2| of disc 20. In this movement the detent 24 disengages from the curved portion 22 and rests in a similar curved portion of the An elongated sleeve 33 is rotatably ESL-is operated to a position'corresponding to loop circuit.

the take-siding position.

The raised transparent portion 8SL of glass 30 permits this symbol to be used both as a key and as a signal for indicating the operated or non-operated condition of the track switch by illumination of either the red lamp R or the green lamp G. I

In Fig. 5 relay 503 is normally energized over a circuit including battery B, winding of relay 503, conductor 506, contacts 51I, and conductors 508 and 501 over a bridged loop including all of the field stations in series. lay 550 is normally energized by way of contacts 565. The pulse generating relay 552 'is' normally energized from positive battery, over 55I, 544 and 559, through the winding of relay 552 to negative battery. 1

In each of the field stations the line relays such as line relay 103, Fig. 7, are energized overa loop circuit including conductors 501 and 508 extending to the dispatchers station. This loop circuit includes contacts 18I, conductor 106, normally closed springs controlled by contact I, and. conductor 101 at each field station. At the last connected field station conductor 101 is connected to conductor 501, thereby completing the Start-in relay 110 is normally energized from positive battery, back contact104, resistance 141, conductor'146, winding of relay 110 to negative battery. Pulse-generating relay 190 is normally energized from positive battery,

' contact 164, conductor 195, resistance 194, to

negative battery.

In accordance with the usual practice the track relays 9T, 8T, 1T, and 6T are normally energized over their respective track sections. Polarneutral relay IUHD is energized from negative battery, back contacts H60, H89, I453, I364, I249, H88, H65, H95, to the common battery point C of the battery associated with the interlock relays. Relay 91-11) is normally energized over the following circuit: from negative battery, back contact I465, I488, I46I, over intervening contacts (not shown), and through the winding of relay 9H1) to the common point of battery C. Relay 9NP is normally energized frornpositive battery, front contact H5I, polar contact H50, H60, H58 and H63, through the winding of relay GNP tonegative battery. Relay SS is maintained energized over the following locking circuit: positive battery, contacts H68, H13, and

conductor I I94.

Relay STS in Fig. 12 is maintained energized over the following circuit: from positive battery through the winding of relay 6-1HP to common point of battery. Relay (is in Fig. 14 is maintained in operated position by way of contacts I451 and I455. Relay GNP is normally energized over a circuit extendin from a distant field station by way of positive battery, back contacts I463 of relay 2HD, conductor I310'and intervening contacts (not shown), I356, I369, I459, I 4H, and through the winding of relay 6NP to Slow-td-release re the negative battery. The normal condition of the track signals in the field are all set at stop position in which position their respective rcd lamps are illuminated in the well-known manner.

The signals on the dispatchers panel are set in corresponding positions with the red lamps illuminated. For example, the signal 9MSL of Fig. 1, corresponding to the track signal 9MS of Fig. 11, has its red lamp illuminated over the following circuit: from positive battery, back contact I05, I55, back contact I4I, I5I, back .contact- I64, and through the filament of the red lamp R to negative battery. The take-siding signal 9SSL, corresponding to the signal SSS of Fig. 11, has its red lamp illuminated over the following circuit: from positive battery, back contact I04, I49, back contact I63, and through the filament of the red lamp R to negative battery. The green lamp of the combined key and track switch signal 8SL is normally illuminated over contacts I82 and I92 to indicate that the track switch TS in Fig. 12 is set in position to route trains over the main track section. The red lamp of signal 1SL, corresponding to the signal IS of Fig. 13, is normally illuminated over a circuit from positive battery, back contact IOI, I09, back contact 22I, 23I, and through the filament of the red lamp to negative battery. The red lamp of signal 6SL, corresponding to the signal 68 of Fig. 13, is illuminated over the followingcircuit: from positive battery, back contact I02, H9, back contact 26I, 21I, and through the filament of the red lamp to negative battery.

Operation of Key-9 It will now be assumed that the dispatcher desires to set the track Signal 9M8, Fig, 11, to proceed position to permit a train traveling from left to right to pass over track sections 9, 8, and 6. In order to set track signal SMS to proceed position the dispatcher will operate the key-9 on the panel. In response to the operation of key-9, relay B9 is energized over the following circuit: from positive battery, contacts I31 of key9, I51, 203, 205, 243, I58, normally closed springs controlled by contact III, I61, and through the winding of relay B9 to negative battery. At contact I3I relay B9 completes an obvious circuit by way of conductor I56 for energizing relay A9, at contact I 32 prepares a point 0 in the locking circuit for itself in case the stick relay S9 is operated, at contacts I35 marks the stop conductor 1 of cable 10 and prepares a circuit for operating relay D9; and at front contacts I36 connects positive battery by way of back contact I41 to conductor 200, thereby completing an energizing circuit for start relay 340. At contacts I2I relay A9, upon energizing, opens a point in the circuit to relay B1 thereby rendering the operation of key1 ineffective at this time. At contacts I22 the circuit extending to relay B6 is likewise opened to prevent its operation in case key6 should be operated at this time. In a similar manner, relay A9 at contacts I 23 opens the circuit to relay B8 to prevent its energization at this time.

Start relay 340, upon energizing, at contacts 34I, completes a circuit for energizing the fast relay 310 by way of 345, 352, 362, 348, 349, and 396. Start relay 340 in addition at contacts 342 tion when the proper selecting relay is operated. Relay 310 operates very quickly when its circuit is completed and also when its circuit is opened,

and at contacts 31! prepares a circuit for relay 453. At contact 312 relay 313 opens its original energizing circuit, but this relay is now held in operated position in series with the upper winding of selecting relay 383 as follows: from positive battery through the upper winding of relay 333, back contacts 332 and 332, 356, 353, front contact 312, conductors 349 and 335 to relay 313 and negative battery. Relay 313 is maintained energized over this circuit while the relay 333, due to the high resistance winding of relay 313, operates only its X contacts 383 to complete a circuit for its lower winding, This circuitmay be traced from positive battery, contact 341; 345, 343, 351, normally closed springs controlled by contact SM, 341, 334, 343, and through the lower winding of selecting relay 383 tonegative battery. Relay 333 completely energizes over the above-traced circuit to operate its remaining contacts and at contact 38I prepares a further point in the circuit to relay 453. At back contacts 332 relay 383 opens the holding circuit of fast relay 313 whereupon the relay 313 very quickly deenergizes to open its holding circuit atcontact 312' before relay 333 can operate when a circuit is prepared for this relay at front contact 382. At contacts 382 relay 333 completes a circuit for relay 313 from positive battery connected to stop conductor 343 at contact 342. Relay 313 at this time is either energized over its original energizing circuit, as previously traced, or over the circuit extending from positive battery,'contact 342, conductor 343, contact 382, conductors 354 and 393. Selecting relay 333 is not operated at this time in response to the operation of fast relay 313 because the upper winding of selecting relay 333 is short circuited as follows: from positive battery, contact 342 over the circuit traced for relay 3.13 and thence by way of conductor 343, contacts 312, 353, conductor 353, back contacts 392,, front contacts 382, and through the upper winding of relay 333 to positive battery. In response to the operation of start relay 343 the selecting relay 383 is operated to complete a circuit for relay 453 as follows: positive battery, contacts 314, 355, 38!, 335, and through the winding of relay 453 to negative battery. From the foregoing it will be seen that start relay 343 associated with the first panel unit at contact 342 has marked the stop conductor 343 so that only the first selecting relay 333 is operated to select the propergroup of codemarking relays.

At this time it may be advisable to explain how other groups of code-marking relays associated with other panel units are selected. For example, it will be assumed that the dispatcher has operated some key in the second panel unit and has therefore caused the operation of start relay 343' over conductor 233' in a manner similar to the operation of start relay 343. At conductor 34! relay 343" completes the circuit for fast relay 313 and at contact 342' connects positive battery to stop conductor 344. Relay 313' operates in the same manner as previously described to cause the operation of the first selecting relay 333 but since the stop conductor 343 is not marked with positive battery potential the second selecting relay 333 is energized over the following circuit in response to the second energization of relay 313: from positive battery through the upper winding of selecting relay 333, front contact 332, back contact 332, conductor 353, contact 353, front contact 352, conductors 343 and336 and through the winding of relay 313 to negative battery. Selecting relay 333 operates to close only its X" contacts 333 over the above traced circuit. When X contacts 393 are closed the following circuit for fully operating the second selecting relay 333 is completed: from positive battery over the previously traced circuit including 341, 345, 343, 35!, 33L 341, X333, and through the lower winding of relay 333 to negative battery. At contact 33!, selecting relay 333 prepares a point in the circuit to the relay in the second code-marking panel unit similar to relay 453, at back contact 332 opens the circuit of fast relay 313to cause its deenergization, at front contact 332 prepares a point in the circuit to the third selecting relay (not shown), at contact 334 opens the circuit of the first selecting relay to cause its deenergization, and at contact 335 connects the stop conductor 344 to the winding of relay 313 to cause the energization of this relay and. to place a short circuit across the upper winding of the third selecting relay (not shown). The reenergization of relay 313 then completes the circuit by way of contacts 311 and 33| over conductor 335 for op erating the relay in the code-marking relays associated with the second panel unit. A separate star-t relay, such as start relays 343 and 343 is provided for each panel unit of the dispatchers panel and likewise a selecting relay such as relays 333 and 333' are provided for each panel unit to enable the proper group of code-marking relays to be selected, in a manner which will be apparent from the foregoing description.

Returning now to the time when code-marking relay 453 energizes as a result of the en'ergization of the first selecting relay 383. Relay 453, upon energizing, at contacts 451 close a bridge across conductors 454 and 455 at contacts 452 connects the first digit stoprclay 433 to the stop .conductor 418, at contacts 453 prepares a point in the circuit to relay 413, and at 432 completes a circuit for energizing relay 533 from positive battery, contact 462, 458, 522, 523, 545, through the winding of relay 533 to negative battery. Relay 533 is the outgoing start relay in the dispatchers coding unit which prepares the circuits to cause the dispatchers coding unit to transmit outgoing impulses to the field stations. Outgoing start relay 533, upon energizing, at armature 53! connects positive battery to the contacts of the digit-counting relays in order to successively connect positive battery to the conductors 481 to 493, inclusive, of cable 83 in order to complete a circuit for energizing the first digit- -stop relay in the connected code-marking relays.

At 532 relay 563 opens a point in the pulsing circuit to the vertical and rotary switch relays to prevent the operation of this switch during the transmission of outgoing codes. At 533 relay 533 completes a locking circuit for itself over conductor 553 and contacts 313 to positive pole of battery. At 554 relay 553 prepares a point in the circuit to relay 583, at 535 opens the circuit to slow-to-release relay 553, and at 533 completes a circuit for energizing the pulsing'relay 513 as follows: from positive battery by way of 563, 523, 532, 523, B11, 455, 413, 43L 45l, 454, and through the winding of pulsing relay 513 to negative battery.

Pulsing relay 513, upon energizing, at contacts 51l opens the loop circuit extending through all of the distant field stations to transmit thefirst pulse of the first digit. The line relays 133 in all of the field stations and the line relay 533 in the dispatchers coding unit deenergize in response to each pulse. Line relay 533, although it follows the outgoing impulses, is ineffective at this time since its impulsing circuit is now open at 

